• Journal of computational fluids engineering
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• v.21 no.2
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• pp.54-61
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• 2016

When spent fuel assemblies from the reactor of nuclear power plants(NPPs) are transported, the assemblies are exposed to short-term operations that can affect the peak cladding temperature of spent fuel assemblies. Therefore, it needs to perform the analysis of heat transfer on spent fuel dry cask during the operation. For 3 dimensional computational fluid dynamnics(CFD) simulation, it is proposed that the short-term operation is divided into three processes: Wet, dry, and vacuum drying condition. The three processes have different heat transfer mode and medium. Metal transportation cask, which is Korea Radioactive Waste Agency(KORAD)'s developing cask, is evaluated by the methods proposed in this work. During working hours, the boiling at wet process does not occur in the cask and the peak cladding temperatures of all processes remain below $400^{\circ}C$. The maximum peak cladding temperature is $173.8^{\circ}C$ at vacuum drying process and the temperature rise of dry, and vacuum drying process occurs steeply.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.85-92
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• 1997

For a InGaAsP buried - heterostructrue $1.3\mu\textrm{m}$ LD with fabry-perot cavity structure, the procedures of ultra-short optical pulse genration ar eanalyzed by simulating the rate equations. Investigting the effects of injected current pulse parameters such as bias $J_b$, pulse width $T_d$ and pulse amplitude $J_p$ on the generated optical pulses, we derive the optimum conditions to obtain a single optical pulse with strong peak value. We also observe that the repetition rate of current pulses needs to be restricted under a certain threshold to generate a train of single optical pulses, and that the period doubling phenomenon takes place by increasing the repitition rate.

• Journal of the korean society of oceanography
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• v.39 no.2
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• pp.148-154
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• 2004

This study describes the realtime monitoring system for water quality conditions in coastal waters. Some issues on the data qualify control and quality analysis are examined along with examples of erroneous data. Three different cases of database produced by the realtime monitoring system are presented and analyzed, namely 1) hypoxic condition, 2) over-saturated D.O. and 3) short-term variability of temperature and D.O. In utilizing the realtime database, D.O. prediction and warning models are developed based on autoregressive stochastic process. The model is very simple, yet, users in various levels from powerful and useful with its ability to send warning messages to users in varous levels from governmental administrative staff to local fisherman, and give them some allowances to cope with the situation.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.215-218
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• 1995

This paper presents an experimental study on the strength and deformation of concrete-filled circular steel short columns. Six specimens of concrete-filled circular short columns were tested under concentric compressive load. For comparsion, three specimens of circular steel short columns were also loaded to failure. The ultimate strength, ductility, and confinement mechanism of columns were compared. In the comparison, the effect of witch-thickness ratio and concrete compressive strength on the behavior of colimns were examed. As a result, the axial load verse axial average strain relationship of concrete-filled circular steel columns was very stable, because of interactions between the concrete and steel, the strength are 13% and 30% larger than the strength extimated by simply superimposed method of the concrete and steel. The ratio of the circumferential to longitudinal strain increment, both measured on the steel suface, was 0.28 up to the longitudinal strain of 0.1%, increases from 0.3 to 0.8 between the strain of 0.1% to 0.3%, and 0.8 beyond the strain of 0.3%

• Environmental Analysis Health and Toxicology
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• v.17 no.1
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• pp.81-93
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• 2002

There were no specific effects for test materials on Sprague-Dawiey (S.D.) rats in clinical symptoms, amounts of food intakes, weight changes, laboratory findings, and pathology after whole body 1, 1-Dichloro-1-fluoroethane (used as coolant, metal cleaner and solvents) exposure (0, 1,500, 3,000, and 6,000 ppm) for 13 weeks (6 hour/day, 5 days/week). However, the loss of capillary vessels in eyeball (pupil) was observed in a female rat among 6,000 ppm group. Though there was a tendency for MCHC (Mean Corpuscular Hemoglobin Concentration) in rat to be decreased (p<0.05), it was not regarded as abnormal because the values were within normal limits. In asthma-stimulation related evaluations. there was also a tendency for inflammatory cell counts in bronchoalveolar lavages to be increased. But it had no statistical significance, and also no dependency on sex and the exposed concentration . Based on this result, the non observed effect level (NOEL) induced by 1, 1-Dichloro-1-fluoroethane inhalation was evaluated in groups with 3,000 ppm below (S.D. Rats, 13 weeks). Finally, it was concluded that the short term exposal of 1, 1-Dichloro-1-fluoroethane is not considered as a asthma stimulant by inhalation despite of some study limitations such as test animals use and short-term exposure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.146-153
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• 2012

RP system which is widely used to reduce the time of product development is to resolve the problem of cutting work. It is a method using laminated thin films to produce many forms. The RP equipment used for this experiment is FDM system. This can produce 3D model with using 3D CAD designed file within a relatively short time. Not only this, this system also through 3D file preparation, 3D product manufacture, removal support these 3 step operating process can easily produce goods, but product can be different from original design. This research has been conducted to minimize this error. To apply to the circular product made a circular specimen and measured several times with 3D scanner and find out average 99.622% of accuracy. This result is applied to RP system, and with this changed design produced a specimen, and found out the accuracy is increased to 99.958%. If this is applied to circular products, we can produce more precise products with less process.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.8
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• pp.119-125
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• 2009

Fabrication of a three-dimensional (3D) metallic mold for multi-production of a microstructure was studied to settle the problem of long processing time in 3D microfabrication. To date, complicated 3D microstructures including 3D photonic crystals, 3D microlens array, 3D filter for microfludics, and something else were created successfully using the two-photon polymerization (TPP) which was considered as paving the way to fabricate a real 3D shape in nano/microscale. However, for those fabrications, much processing time and efforts were inevitably required. To solve this issue, a simple and effective way was proposed in this paper; 3D master patterns were prepared using TPP, and then counter-shaped Ni molds were fabricated by electroforming process. By using these molds, 3D microstructures can be reproduced with short-processing time and low-effort comparing to the conventional approach, TPP We report some parameters to fabricate a metallic mold precisely.

• ETRI Journal
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• v.6 no.4
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• pp.3-8
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• 1984

Frequency division multiplexed 3ch. Color TV signals have been transmitted via optical fiber by employing $1. 3\mum$ InGaAsP DH-laser diode, graded index optical fiber and Ge-APD as optical components. Overall system margin of 20 dB was realized at weighted SNR of more than 49 dB. With this system margin, measured DG and DP were less than 10% and $5^{\circ}$respectively. Throughout this experiment, it was confirmed that multichannel TV signals could be economically transmitted over optical fiber in short haul networks. This paper describes system outlines and hardware implementation results.

• Journal of Fashion Business
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• v.10 no.6
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• pp.28-37
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• 2006

The purpose of this work is to present three-dimensional models of plain fabrics having various warp and filling yarn diameters. In order to simulate a woven fabric, a 3-dimensional CAD software with NURBS modeling capability was used. Final rendering was performed on the fabric model. It was demonstrated that the changes in yarn diameter could be three-dimensionally modeled through the use of fabric geometry and the 3D CAD. A short RhinoScript program was composed to implement the data importing and model building on the 3D CAD.

• Electrical & Electronic Materials
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• v.6 no.4
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• pp.330-338
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• 1993

Channel의 폭과 길이가 15 x 15.mu.m, 15 x 1.5.mu.m, 1.9 x 1.7.mu.m인 비휘발성 SNOSFET EEPROM 기억소자를 CMOS 1 Mbit 설계규칙에 의하여 제작하고 체널크기에 따른 $I_{D}$- $V_{G}$특성 및 스위칭 특성을 조사하여 비교하였다. 게아트에 전압을 인가하여 질화막에 전하를 주입시키거나 소거시킨 후 특성을 측정한 결과, 드레인전류가 적게 흐르는 저전도상태와 전류가 많이 흐르는 고전도상태로 되는 것을 확인하였다. 15 x 15.mu.m의 소자는 전형적인 long channel특성을 나타냈으며 15 x 1.5.mu.m, 1.9 x 1.7.mu.m는 short channel특성을 보였다. $I_{D}$- $V_{G}$ 특성에서 소자들의 임계 문턱전압은 저전도상태에서 $V_{W}$=+34V, $t_{W}$=50sec의 전압에서 나타났으며 메모리 윈도우 폭은 15 x 15.mu.m, 15 x 1.5.mu.m, 1.9 x 1.7.mu.m의 소자에서 각각 6.4V, 7.4V, 3.5V였다. 스위칭 특성조사에서 소자들은 모두 논리스윙에 필요한 3.5V 메모리 윈도우를 얻을 수 있었으며 논리회로설계에 적절한 정논리 전도특성을 가졌다.특성을 가졌다.다.다.